The Lords’ demanded protections for the rights of EU citizens living in the UK, and a written guarantee that Parliament will have a “meaningful vote” on the final terms of the UK’s departure.

Mrs May has indicated Parliament will get a say, but has said she would rather “walk away” from the EU than accept a “bad deal”, and would not return to negotiations if MPs and peers reject the Brexit package.

‘No strings’

Mr Davis urged MPs to throw out the Lords’ amendments and send the bill back to them again for final approval “in its original form”.

“However they voted in the referendum, the majority of people now want the prime minister to be able to get on with the job,” he said.

“MPs passed straightforward legislation allowing the government to move ahead with no strings attached.”

“It is clear from our evidence that a complete breakdown in negotiations represents a very destructive outcome, leading to mutually assured damage for the EU and the UK,” the Commons foreign affairs committee said.

“Both sides would suffer economic loss and harm to their international reputations.”

Failure to prepare for such outcome would be a “serious dereliction of duty,” the MPs said.

‘Guesswork’

Shadow foreign secretary Emily Thornberry said the government had been “reckless” not to prepare for a Leave vote and also in its approach to Article 50 negotiations.

“All we have heard from the government so far is that if there is no deal, they are prepared to ‘break the British economic model’.

“There are some very serious issues highlighted in this report which must be addressed. It is completely inadequate to brush these questions off and claim what would happen without a deal is ‘an exercise in guesswork’.”

A government spokesman said Mr Davis had briefed the cabinet last month “on the need to prepare not just for a negotiated settlement, but for the unlikely scenario in which no mutually satisfactory agreement can be reached”.